The present invention concerns the field of inventory management, and more particularly concerns using RFID tags to locate devices and other assets having a given state.
Radio frequency identification (RFID) tags provide an inexpensive way to manage inventory by enabling the process of locating various devices. Here, locating a device means determining its coordinates or position in a spatially referenced sense, where the term coordinates is used broadly. The coordinates can be, for example, latitude and longitude, distance and direction from a known reference point, proximity to a given intersection such as the intersection of aisles in an office or warehouse, a shelf label location in a warehouse, a room number in an office building, and so forth.
In some situations, an RFID infrastructure can be set up having a number of stationary RFID tag readers located throughout a building or campus, and an edge controller to collate or consolidate information provided by the RFID tag readers. Such a system, which may be called an RFID networked-system application, can locate or track monitored devices that are equipped with RFID tags as the devices move within a geographic area. For example, such a system may be used to locate and track equipment carts in a hospital, forklifts or textbooks in a warehouse, and the like.
Although such RFID networked-system applications are quite effective in locating and tracking devices, they are unable to provide any information concerning the devices beyond their locations. In particular, RFID networked-system applications fail to convey any information regarding the state of the monitored devices. This can be a significant limitation. For example, hospital staff may use such a system to locate the nearest equipment cart, only to find that the nearest cart is presently in use. Likewise, a factory foreman may locate the nearest forklift using such as system, only to find that its battery is discharged.
Thus, there is a need to improve RFID networked-system applications by enabling them to provide state information in addition to locations and trajectories.